1. Field of the Invention
This invention relates to a semiconductor device having a semiconductor chip coated with a sealing resin layer.
2. Description of the Related Art
Recently, the wiring electrical resistance has been reduced and a relative dielectric constant of an interlayer insulation film have been made smaller for the purpose of acceleration of a semiconductor device such as an LSI. Specifically, the wiring material has been shifted from aluminum (Al) to copper (Cu). As for the interlayer insulation film, too, a low relative dielectric constant insulation film (low-k film) such as a silicon oxide film doped with-fluorine or a silicon oxide film containing organic components has been adopted together with a simple silicon oxide film.
The interlayer insulation film with low relative dielectric constant is formed by lowering the density of the material or excluding the dielectric polarization of the material. To lower the density of the material, for example, the material is generally made porous. Since the interlayer insulation film with low relative dielectric constant is low in film density, its mechanical properties such as the Young's modulus are generally small. In other words, the material of the interlayer insulation film with low relative dielectric constant is low in strength. Furthermore, the interlayer insulation film with low relative dielectric constant has a film structure of low polarity to lower the dielectric constant in the film. For this reason, if the interlayer insulation films with low relative dielectric constant or the interlayer insulation film and the other interlayer insulation film are laminated, adhesion strength in the interface between the laminated films is low.
Such a low strength in the interlayer insulation film with low relative dielectric constant and such a low adhesion strength in the interface between the interlayer insulation films in the laminated structure including the interlayer insulation films with low relative dielectric constant, particularly become serious troubles in the lamination process to form the wiring of the semiconductor device in the multilayer structure. They also cause serious problems such as peeling and the like in a packaging process executed after the lamination process. In particular, the factor bringing about a serious damage is thermal stress from a sealing resin layer which serves as an environmental protection film. The sealing resin layer is generally smaller in Young's modulus by one or more digits and greater in coefficient of linear expansion by one or more digits, than that of silicon substrate. For this reason, great thermal stress is applied to the interlayer insulation film, in various kinds of processings that make thermal influence, such as curing the resin in a resin sealing step, reflowing the solder during mounting of the semiconductor device on the printed wiring board or the like, TCT (Temperature Cycling Test), and the like. As a result, the thermal stress breaks the interlayer insulation film with low relative dielectric constant such as a low-k film which has low polarity and low mechanical strength, and causes peeling in the interface. A prompt solution is therefore demanded to solve the problem.
On the other hand, Jpn. Pat. Appln. KOKAI Publication No. 9-246464 discloses a semiconductor device in which a side surface of an LSI chip or an overall surface thereof other than a bonding pad is coated with insulating resin and sealed by a sealing resin layer to reduce an external force which is to be applied directly to the side surface or entire surface of the LSI chip together with the curing and shrinking force of the sealing resin and the thermal stress of the sealing resin. The publication also discloses that the insulating resin includes resins such as epoxy, acryl, polyimide, urethane and the like that are cured by heat treatment, exposure to ultraviolet radiation, room-temperature maintenance and the like. In addition, the publication also discloses that the Young's modulus of the insulating resin should be smaller than that of the sealing resin.
In the invention of Jpn. Pat. Appln. KOKAI Publication No. 9-246464, however, since the insulating resin needs to be used as well as the sealing resin, the structure of the semiconductor device becomes complicated and interfaces considered as the peeling factor are newly increased problems, which increases the manufacturing costs.